Bitmap image format based on the Interchange File Format (.IFF files); originally designed for use with Amiga chipsets; stores bitplanes, which contain one bit of data for each image pixel; supports bitonal and color images, as well as RLE (Run-length encoding) compression.

ILBM files were used by early graphics editing programs, such as Electronic Arts Deluxe Paint. They are still viewable using several image viewers. NOTE: Interleaved Bitmap files can also be saved with the .LBM extension. They are sometimes also seen as .IFF files, although the ILBM format does not support all features specified by the Interchange File Format.